US3493462A - Nonpatterned,nonwoven fabric - Google Patents

Description

Feb. 3, 1970 NH G, my, ETAL 3,493,462

NONPATTERNED, NONWOVEN FABRIC Filed March 11, 1968 7 Sheets-Sheet 1 24 INVENTORS WILLIAM mm BUNTING. m. FRANKLIN muss EVANS A DAVID ELLIS HOOK Feb. 3, 1970 w w JR" ETA-L 3,493,452

NONPATTERNED, NONWOVEN FABRIC Filed March 11, 1968 7 Sheets-Sheet 2 FIG. 3 F I G. 4

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INVENTORS WILLIAM WALLAR HUNTING, JR. FRANKLIN JAMES EVANS DAVID ELLIS HOOK ATTORNEY Feb. 3, 1970 Filed March 11. 1968 W. W. BUNTING, JR, ET AL 7 Sheets-Sheet 5 4-111 74% FlG.ll

k! 25' B 11 n2 r3 L Fl G. 39

INVENTORS 5 WILLIAM WALLAR aummc, JR. k, FRANKLIN muss EVANS 0 DAVID ELUS noon 8 \l f/ ATTORNEY Feb. 3, 1970 w w. BUNTING, JR" ET AL 3,493,462

NONPATTERNED, NONWOVEN FABRIC u INVENTORS mum WALLER aummc, JR. FRANKLIN JAMES EVANS nvm Ems noon v BY ATTORNEY Feb. 3, 1970 -w w. BUNTING, JR. ET 3,493,452

NONPATTERNED NONWOVEN FABRIC Filed March 11, 1968 7 Sheets-Sheet 5 FIG=8 INVENTORS WILLIAM I IALLAR BUNTINILJR. FRANKLIN JAMES EVANS DAVID ELLIS HOOK ATTORNEY Feb. 3, 1970 w w BUNT'ING, JR" ET AL NONWOVEN FABRIC NONPATTERNED 7 Sheets-Sheet 6 Filed March 11. 1968 FIG.

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FIG-l5 FIG SR R u O T G N m E v m% R F. I. M w W l. u w

FRANKLIN JAMES EVANS DAVID ELLIS HOOK ATTORNEY Feb. 3, 1970 'iled March 11, 1968 O. I INCH 0. l lNCH O.| INCH W. W. BUNTING, JR, ET AL NONPATTERNED, NONWOVEN FABRIC '7 Sheets-Sheet 7 WILLIAM WALLER BUNTING, JR. FRANKLIN JAMES EVANS DAVID ELLIS HOOK ATTORNEY United States Patent O 3,493,462 NONPATTERNED, NONWOVEN FABRIC William Wallar Bunting, Jr., Franklin James Evans, and David Ellis Hook, Wilmington, Del., assignors to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Continuation-impart of abandoned application Ser. No.

584,627, Sept. 22, 1966, which is a division of application Ser. No. 208,136, July 6, 1962. This application Mar. 11, 1968, Ser. No. 712,070

Int. Cl. D04h 3/08; D06c 1/06 US. Cl. 161-169 2 Claims ABSTRACT OF THE DISCLOSURE Processes are disclosed for treating fibrous sheet materials with streams of water or other suitable liquid. Fibrous sheet material on a supporting member is traversed with the streams to entangle the fibers in a manner which imparts strength and stability without the need for binder. The examples illustrate application of the process to a variety of fibrous sheet materials, including treatment of batts of loose staple fibers or continuous filaments, to form coherent, highly stable, strong nonwoven fabrics which are randomly entangled and substantially nonpatterned or which have a repeating pattern of closely spaced lines of fiber entanglement.

CROSS-REFERENCES TO RELATED APPLICATIONS This is a continuation-in-part of copending application Ser. No. 584,267, filed Sept. 22, 1966, now abandoned as a division of Ser. No. 208,136, filed July 6, 1962, and now abandoned.

BACKGROUND OF THE INVENTION This invention relates to novel textile products and to a process for their production. More particularly, it relates to nonwoven fabrics obtained by subjecting bulk fibrous materials to the action of liquid streams.

The prior art discloses various processes in which fluids under pressure have been used to treat textile materials. For example, dispersed streams of water, provided by a solid cone spray nozzle supplied with Water at 70 to 100 pounds per square inch gauge pressure (p.s.i.g.), have been applied through spaced apertures against a fibrous starting material so as to rearrange laterally the individual fibers into a pattern determined by the pattern of the apertures. These prior art product rely on binder to attain strength.

Guerin US. Patent No. 3,214,819 issued Nov. 2, 1965, teaches the formation of noncored felts, cored felts and felts with a backing, by applying jets of liquid to a plurality of layers of loosely associated textile fibers to produce a reorientation of some fibers between laminations to provide a fiber-locking and entanglement, in the product, having a strength equal to a normal needle loomed fabric and with greater flexibility and diversification. The patent also discloses that when an adhesive such as resin 3,493,462 Patented Feb. 3, 1970 in liquid form is added the binder is permeated through the material to anchor the fibers in their new oriented form and increase the tensile strength and abrasion resistance. The present invention provides important improvements over the teaching of the Guerin patent.

SUMMARY OF THE INVENTION The present invention provides improvements in the process for producing substantially nonpatterned nonwoven fabric from bulk fibrous materials wherein a layer of fibers on a supporting member is treated with liquid jet streams to consolidate the fibers into a self-coherent fabric. The invention provides a more efiicient process which is suitable for producing more uniform and stronger nonwoven products. The invention is particularly useful for processing nonfeltable fibers and filaments, i.e., synthetic and cellulosic fibers and filaments, including cotton, rayon and cellulose derivatives. Preferred embodiments provide new smooth-surfaced textile fabrics having substantially uniformly dense structures. Other advantages will become apparent from the specification and claims.

The process of the present invention comprises supporting a layer of fibrous material on a smooth supporting member for treatment, jetting liquid supplied at a pressure of at least 200 pounds per square inch gauge from orifices less than about 0.015 inch in diameter to form fine streams having over 23,000 energy flux in footpoundals/inch second at the treatment distance, and traversing the supported layer of fibrous material with the streams along paths centered less than about 0.1 inch apart to apply a treatment energy of at least 0.1 horsepower-hour per pound of fabric product.

The above process is applicable to continuous filaments as well as fibers of textile length and shorter. Unless otherwise indicated these will all be referred to as fibers. The fine liquid streams are advantageously formed by jetting water from orifices 0.002 to 0.015 inch in diameter arranged in a line in a manifold at a frequency of at least 10 orifices per inch, and preferably 20 to 40 orifices per inch, although a frequency of 5 orifices per inch can also be used as illustrated in the examples. Orifices must be used which will provide at least 23,000 footpoundals/inch second of energy flux at the treatment distance, as explained in detail subsequently. Preferably the streams are essentially columnar.

The rate at which the layer of fibrous material is traversed with the streams and the number of times the layer is treated should provide a total treatment energy of at least 0.1 horsepower-hour per pound of fabric (HP-hr./lb.). As subsequently explained, it is frequently desirable to apply much higher treatment energies. Ade quate treatment with the streams will provide strong, durable fabrics. For products having sufiicient surface stability to withstand repeated washing without the use of binders, the treatment energy is preferably greater than 1 HP-hr./lb. Preferably, water pressures of at least 500 p.s.i.g. are used to reduce the treatment time.

During treatment, the layer of fibrous material is supported by a member which does not influence the arrange ment of the fibers into a pattern dependent on the supporting surface. This type of member will be simply called a smooth supporting member hereinafter, and it may be a solid plate, bar, roll or the like, or it may be a relatively smooth screen of sufficiently fine mesh so that the fibers are not rearranged into any pattern dependent on the screen pattern.

The process of the present invention may be used to produce two types of nonwoven fabrics, namely (1) a line-entangled product and (2) a substantially uniformly entangled product, depending upon whether the streams of jetted liquid are allowed to act directly on the fibrous layer or are oscillated or interrupted in their passage toward the layer, the layer being treated on a supporting member as discussed above. For either type of fabric, it has been found that a synergistic effect with respect to producing a strong fabric (preferably having a tensile strength of at least 2 lbs/in. per oz./yd. is obtained by the use of small diameter orifices (0.002 to 0.010 inch in diameter), which are closely spaced (at least per inch and preferably to 40- per inch) and high pressures (greater than 200 p.s.i.g. and preferably at least 500 p.s.i.g.), for products weighing less than 10 ounces per square yard.

When the process of the present invention is operated so that essentially columnar streams of liquid, such as water, emerge from the orifices and pass directly into contact with the layer of fibers (on the supporting member), along parallel, continuous paths, which are straight, curved or zig-zag, one produces a nonwoven fabric having lines of entanglement in a straight, curved or zig-zag pattern determined by the paths of the streams and corresponding in number and frequency to the number and frequency of the orifices. This type of line-entangled product may have a distinct jet-track pattern. The jet-track pattern can be emphasized by carrying out the treatment so that the parallel streams pass repeatedly along the same paths, as illustrated in Example II. Entanglement and hence strength can be increased by repeated treatment or by prolonged treatment, for example by slow passage of the streams over the layer.

When the above treatment is carried out while oscillat ing the jet streams at high frequency (e.g., 300 cycles per minute for 2 yards/minute web speed), or while interrupting them, soft, smooth-surfaced and substantially uniformly dense products can be made even from lightweight materials, e.g., as shown in Example IX. Interrupting the jet streams before they reach the fibrous layer is carried out so as to form intermittent essentially columnar streams. A preferred method of accomplishing this is to place a screen or the like (referred to hereinafter as a streams-interrupting-member) in the path of the jet streams at a point between the orifices and the plane of the fibrous layer and to oscillate the streams-interruptingmember through the streams to provide a high frequency of interruption during treatment. The streams-interrupting-member is not used to restrain the fibrous layer or to influence rearrangement of the fibers of the layer into a pattern. Preparation of nonwoven textile fabrics by this method is illustrated in Example X.

The substantially nonpatterned, nonwoven textile fabrics of the present invention are generally smooth-surfaced, dense and strong; their strength is due to fiber entanglement, which is achieved without the use of feltable fibers (such as wool) or of conventional needle-punching.

In particular, the substantially nonpatterned nonwoven fabrics of the present invention are characterized by having a substantially uniformly dense structure of interentangled fibrous material selected from the group consisting of cellulosic and synthetic textile fibers and filaments, fiber segments oriented transversely to the plane of the fabric being randomly distributed as opposed to clustered, the fabric being characterized by a fiber entanglement completeness F of at least 0.5 and an entanglement frequency f of at least per inch when measured in the bond-free condition, and the fiber interlock value being at least 10.

A particular advantage of the present invention is that these dense, substantially nonpatterned, nonwoven fabrics can be made at low basis weights of less than 8 ounces per square yard, and much lower, as shown in the exam les.

p The substantially uniformly dense structure of the products is readly apparent when viewed by transmitted light as illustrated in FIGURE 17. The nature of the interentangled fiber structure is illustrated in FIGURES 18 to 20, and can be seen with a microscope. The substantial absence of clusters of fiber segments oriented transversely to the plane of the fabric distinguishes these products from heavy needle-punched felts or similar products of processes in which fiber webs are treated at spaced sites. FIGURE. 21 illustrates the clusters of transverse fiber segments in a commercial needle-punched felt. When such photomicrographs are evaluated for clusters as disclosed near the end of the specification, clustering coefiicients of less than 2.5 are found for structures of types shown in FIGURES 18 to 20, as contrasted with a clustering coefilcient of 3.8 for FIGURE 21.

Determination of entanglement completeness, entanglement frequency and fiber-interlock values is described near the end of the specification. By bond-free is meant that the fibers of the nonwoven fabric are not adhered with hinder or interfiber fusion bonds. In other words, the nonwoven fabric is tested to determine the properties due solely to the interentangled fiber structure.

By interentangled is meant that the individual fibers of the structure are intertwined, tangled, interlaced and otherwise joined with each other so as to be virtually inseparable. The process may be applied to preselected areas of the layer of fibrous material up to and including its entire area. When the treated area is viewed in crosssection, it is observed that a number of fiber segments have been reoriented in the direction generally perpendicular to the plane of the nonwoven fabric by the action of the streams. It is believed that these fibers contribute to the strength of the nonwoven fabric by serving to tie other fibers in place.

The term layer of fibrous material includes any layer composed of fibrous elements in the form of staple fibers, continuous filaments, and/or yarns in the form of mats, batts, webs or the like and including layered composites and blends thereof.

Nonwoven fabrics having particularly high levels of drape and conformability can be obtained by using crimpable, spontaneously elongatable, or elastic fibers as one of the components of the fibrous sheet material and developing the latent properties of the fiber after formation of the nonwoven fabric.

BRIEF DESCRIPTION OF THE DRAWINGS This invention can be more thoroughly understood by the following discussion, with reference to the drawings wherein:

FIGURE 1 shows a schematic view of one type of apparatus for carrying out the process of this invention.

FIGURES 2a2c are axial cross-sectional views of suitable nozzles.

FIGURE 3 is a cross-sectional view, taken along the longitudinal axis, of a nozzle which may be used to produce intermittent columnar flow.

FIGURE 4 is a schematic view of one apparatus for carrying out the process of this invention.

FIGURE 5 is a schematic isometric view of an apparatus for the high speed production of a continuous nonwoven fabric.

FIGURE 6 is a schematic isometric view of an apparatus for the high speed, continuous production of nonwoven fabrics.

FIGURE 7 is a schematic side view of apparatus for continuously feeding and opening staple fibers, forming a web and jet treating the web to form nonwoven fabrics.

FIGURE 8 is an enlarged side-sectional view of one of the jet-treating machines in FIGURE 7.

FIGURE 9 is an exploded isometric view of one of the jet manifolds in FIGURE 8.

FIGURES l0, l1 and 12 are diagrammatic representations of cross-sections of a batt of fibers at three stages of treatment.

FIGURE 13 is a photograph showing the upstream face of the nonwoven fabric of Sample F of Example 1. The upstream face is the one nearest the jet streams during final treatment.

FIGURE 14 is a photograph showing the downstream face of the fabric of FIGURE 13. The downstream face is that adjacent the supporting screen during final treatment.

FIGURE 15 and FIGURE 16 are X enlarged vieWs of the fabrics of FIGURES 13 and 14.

FIGURE 17 is a photomicrograph taken by light transmitted through fabric A of Example 10 to show the absence of pattern. The magnification is indicated by the scale beside the figure.

FIGURES 18 to 20 are photomicrographs, made with a scanning electron microscope, showing sectional views of the interiors of fabric produced as described in Examples 10A, 10B and 11, respectively. The section is taken in the plane of the fabric, approximately midway between the two faces. The scales beside the figures indicate magnification.

FIGURE 21 is a photomicrograph of a microsection slice taken approximately midway between the two faces of a commercial needle-punched felt to illustrate the transverse fiber clusters characteristic of such treatments. Magnification is shown by the scale beside the figure.

EQUIPMENT A relatively simple form of equipment for treating fibrous webs with water at the required high pressure is illustrated in FIGURE 1. Nitrogen under a pressure of 2000 lbs/sq. in. in a bottle 1 is connected through a regulating valve 2 and pipe 3 to one chamber 4 of a hydraulic accumulator 5. The hydraulic accumulator is separated into two chambers 4 and 6 by a flexible diaphragm 7. The second chamber 6 is connected to a nozzle 20 through a pipe 8 in which a valve 9 is provided. Water is supplied to the second chamber from a source of water (not shown) through a valve 10 and a pipe 11. When water is added, pressure is released from the first chamber through pipe 12 by opening a valve 13. Starting with an unpressurized situation, the system is charged by closing regulating valve 2, opening valve 13 so that atmospheric pressure prevails in the system, closing valve 9 and opening valve 10 to admit water at a pressure of about 40 lbs/sq. in. gauge; the water pushes the diaphragm 7 of the accumulator 5 to the right into chamber 4, thus filling chamber 6. After chamber 6 is filled, valves 10 and 13 are closed, regulating valve 2 is opened and adjusted to deliver nitrogen at about 2000 lbs/sq. in. gauge to the chamber 4; this pressurizes the Water in chamber 6 so that the system is ready to deliver water to the nozzle 20 through line 8 whenever valve 9 is opened. The nozzle 20 may be any one of a variety of nozzles depending on the efiect desired. Various types of nozzles which may be used are shown in FIGURES 2a2c.

The fibrous sheet material to be treated 14 is placed on a generally rectangular wire screen carrier 15 situated below the vertically disposed nozzle and supported on a horizontal, fiat plate 16. A jack 17 of the scissors type supports plate 16 so as to be vertically adjustable, providing for adjustment in the distance between the tip of the nozzle 20 and the screen 15. The screen, in this case, is an ordinary woven one of 80 by 80 mesh per inch and is made of 0.005-inch diameter stainless steel wire. The screen is not secured to plate 16 but is free to be moved manually in a horizontal plane in any direction.

The plate 16 is provided with a vent hole 18 which is vertically aligned with the axis of the nozzle 20 so as to pass liquid which issues from the nozzle; a tray 19 is adapted to catch any liquid which falls through vent hole 18.

The following example will illustrate operation of this apparatus for treating a staple fiber batt to produce a jettrack-patterned product. A loose batt 14 of randomly arrayed staple fibers is laid on screen support 15. The jack 17 is adjusted vertically so as to position the upper face of the batt about 1 inch below the tip of nozzle 20. The batt is then exposed to the action of the high velocity stream of water while simultaneously being passed horizontally along a straight line in one direction. A series of batts, ranging in thickness from to 3 inches are processed in this manner, successive passes being made along lines parallel to the first pass. Some of the batts are also subjected to successive passes along lines at right angles to the first passes. In all instances, it is observed that along the lines of liquid treatment, the fibers of the batt are driven generally downward, thus tending to consolidate the batt; in addition, the fibers are entangled and intertwined with one another, in general, in a discrete continuous line corresponding to the path of treatment of the liquid stream.

The nozzle shown in FIGURE 2a is adapted to be connected to pipe line 8 and consists of a body 21 having an axial bore 22 which is generally closed at the bottom end except for a pair of orifices 23, 24 which are coplanar with each other and with the axis of the bore 22 and are inclined toward each other, in the direction of the liquid fiow, at an included angle A. This angle is about 20 to 25 and the orifices are 0.007 inch in diameter. Liquid streams emerging from the orifices 23, 24 are continuous but tend to break up as the two streams impinge on each other. In the use of this type of nozzle, the sheet material is placed either above or at the point of intersection of the streams.

A variation of the nozzle of FIGURE 2a is shown in FIGURE 2b, in which a pair of 0.007" diameter orifices 23, 24- are disposed parallel to each other and coplanar with the bore 22.

The nozzle shown in FIGURE 2c is similar to that shown in FIGURE 2a, except that a single central orifice 24 is used; this orfice is coaxial with the bore 22. At a pressure of about 1,000 lb./sq. in., a single 0.007-inch diameter orifice will deliver about 14.5 lbs. of water per hour, and at 2,000 lbs/sq. in., 20.5 lb./hr.

The nozzle shown in FIGURE 3 can be used when intermittent flow is desired. It resembles a diesel-engine type of fuel injection nozzle. The body 21 has an axial bore 22 in which a close-fitting cylindrical plunger 30 is situated. The plunger has a conical tip 31 adapted to form a fluid-tight seal in a mating conical seat 32 at the lower part of the bore 30. Axial passage 33, of smaller diameter than bore 22, opens downward from the conical seat. An annular space 34 is cut into the conical seat. A liquid supply passage 35 is drilled downward through body 21 along side of bore 22 to communicate with the annular space. Plunger 30 is urged downward against the conical seat at a pressure determined by adjusting a spring 36. When this pressure is exceeded by liquid supplied to space 39 through passage 35, then plunger 30 is forced upward and liquid passes downward through axial passage 33. A nozzle tip 37 screws onto the lower end of body 21 and is provided with orifices, such as orifices 24, 25, 26, which direct liquid from passage 33 downward in columnar flow. Any of the orifice arrangements shown in FIGURES 2a2c can be used. Another suitable tip is provided with a central orifice 0.50 mm. in diameter surrounded by six orifices 0.45 mm. in diameter and equally spaced on a 50 included angle cone in the manner illustrated for orifices 24, 25 and 26.

When the nozzle of FIGURE 3 is used in the apparatus of FIGURE 1, intermittent impulses of high pressure liquid are supplied by an intensifier 40, a standard piece of equipment which, when supplied with driving air at a pressure of 40 p.s.i.g. will boost the water pressure to about 20,000 pounds per-square-inch gauge in short pulses having a frequency of about one pulse per second. This is supplied to nozzle through line 41 provided with a throttling valve 42. Water and air are supplied to the intensifier through lines 43 and 44, respectively. The hydraulic accumulator system described previously is not used when the intensifier is used, so line 8 is disconnected. The fibrous sheet material is treated in the same manner as before but the pulses of high velocity liquid, formed with the intensifier and nozzle of FIGURE 3, pierce the sheet material at intervals along the path of traverse under the nozzle. Short discrete seam-like lines of entanglement and/ or point seams are produced at each spot pierced by the intermittent stream. The frequency and duration of the liquid pulses may be controlled by adjusting spring 36, by throttling with valve 42, and by selection of the nozzle tip 37, to produce streams in the range of 0.0005 to 0.005 inch in diameter which impinge on the fabric at pressures of the order of 3000 pounds per square inch in the desired seaming pattern.

Instead of using individual nozzles and subjecting the fibrous sheet to a number of successive passes, a plurality of nozzles arranged in a row and spaced any desired distance apart may be used to increase the area of treatment in a single pass. By this method, parallel seams, i.e., lines of entanglement, as close to each other as 0.025 inch per inch) or less can be produced in batt materials in two directions, changing their appearance to that of a woven fabric. Apparatus for the continuous production of a non-woven fabric by this process is shown schematically in FIGURE 5.

In the apparatus, a horizontal, belt-type screen conveyor is adapted to transport a batt of fibers 28 in the direction of the arrow. Transverse of the conveyor is a plurality of spaced stationary nozzles 51 which are adapated to modify the batt along lines disposed in the direction of batt travel as denoted by the lines 52. Downstream of the nozzles 51 are one of more nozzles 53 which are arranged to be reciprocated transversely of the batt (by a mechanism not shown) so as to modify the batt along the lines 54 which are generally perpendicular to the lines 52. Still further downstream is a series of rollers 55a, )5, c and d which change the direction of the modified batt, causing it to be momentarily immersed in a liquid filled tank 56 for shrinkage, dyeing, bleaching, etc., as desired. At the extreme right is a windup 58 for receiving product 57. The roller 550! may be used for pressing or wringing the modified batt, heat treating or drying it, embossing it, etc.

In operation, a batt of fibers 2-8 is advanced from left to right under the various nozzles where is it modified (either continuously or intermittently) in one or more directions; if desired, the batt then travels to the liquid bath where it is shrunk, being subsequently dried or partially dried, and finally wound on a suitable core.

An apparatus for the continuous treatment of fibrous sheets is shown in FIGURE 4. Water at normal city pressure of approximately pounds/sq. in. gauge is supplied through valve 81 and pipe 82 to a high pressure hydraulic pump 83. The pump may be a double-acting, single plunger pump operated by air from line 84 (source not shown) through pressure regulating valve 85. Air is exhausted from the pump through line 86. Water at the desired pressure, e.g., 2000 lbs./ sq. in., is discharged from the pump through line 87. A hydraulic accumulator 88 is connected to the high pressure water line 87. The accumulator serves to even out pulsations and fluctuations in pressure from the pump 83. The accumulator is separated into two chambers 89 and 90 by a flexible diaphragm 91. Chamber 90 is filled with nitrogen at a pressure of to of the desired operating water pressure and chamber 89 is then filled with water from pump 83. Nitrogen is supplied through pipe 92 and valve 93 from a nitrogen bottle 94 equipped with regulating valve 95. Nitrogen pressure can be released from the system through valve 96. Water at the desired pressure is delivered through valve 97 and pipe 98 to manifold 99 supplying orifices 100. The fine, essentially columnar streams of water 101 emerging from orifices impinge on the material being treated 102, which is supported by conveyor screen 103.

The streams are traversed over the web, by moving the conveyor screen 103 and/or the manifold 99, until the web is treated in the desired areas at high energy fiux. In general, it is preferred that the initial fibrous layer be treated by moving conveyor screen 103 under a number of fine, essentially columnar streams, spaced apart across the width of the material being treated. Rows or banks of such spaced-apart streams can be utilized for more rapid, continuous production of nonwoven fabrics. Such banks may be at right-angles to the direction of travel of the Web, or at other angles, and may be arranged to oscillate to provide more uniform treatment. Streams of progressively increasing energy flux may be impinged on the web during travel under the banks. The streams may be made to rotate or oscillate during production of the nonwoven fabrics, may be of steady or pulsating flow, and may be directed perpendicular to the plane of the web or at other angles provided that they impinge on the web at sufiiciently high energy flux.

Another apparatus suitable for the continuous production of nonwoven fabrics in accordance with the present invention is shown schematically in FIGURE 6. A pump 65, which may be one of the types used for supplying water to high pressure steam boilers, is used to provide liquid at the required pressure. A fibrous layer 60, prepared by conventional means such as a card machine or random web air-laydown equipment, is supplied continuously to a moving carrier belt 61 of flexible foraminous material, such as a screen or a solid belt. The carrier belt is supported on two or more rolls 62 and 63 provided with suitable driving means (not shown) for moving the belt forward continuously. Six banks or orifice manifolds are supported above the belt toimpinge liquid streams 64 on the fibrous layer at successive positions during its travel on the carrier belt. The fibrous layer passes first under orifice manifolds 66 and 68, which are adjustably mounted. Orifice manifolds 74, 75, 76 and 77 are adjustably mounted on frame 78. One end of the frame is supported for movement on a bearing 79, which is fixed in position. The opposite end of the frame is supported on oscillator means 80 for moving the frame back and forth across the fibrous layer.

High pressure liquid is supplied from the reservoir to the orifice manifolds through pipe 18. Each manifold is connected to pipe 18 through a separate line which includes flexible tubing 48, a needle valve 45 for adjusting the pressure, a pressure gage 46, and a filter 47 to protect the valve and jet orifices from foreign particles. As indicated on the gages in the drawing, the valves are adjusted to supply each successive orifice manifold at a higher pressure, so that the fibrous layer 60 is treated at increasingly higher energy flux during travel under the liquid streams 64. However, the conditions are readily adjusted to provide the desired treatment of diiferent initial fibrous layers.

FIGURE 7 illustrates a combined apparatus for continuous processing of staple fiber stock, as received from the supplier, to convert the material into a nonwoven fabric. The stock is fed through a conventional opener or picker 788 and the opened stock is carried on conveyor belt 789 to a conventional card machine. The stock is fed by lickerin 780 to card cylinder 781 where the fibers are combined, the fibers are collected on dotfer 785 and are taken off through calender 786 and are introduced into a layer-forming apparatus. The fibers are carried on elevating apron 755 until removed by stripper apron 758 and are collected on condenser roll 763 to form a preliminary layer. The lickerin 767 separates the fibers and the fibers are deposited on condenser roll 771 to form a uniform layer of randomly arranged fibers. The layer is supported on conveyer belt 774 until it passes through calender 775 to be made s-ufficiently selfsupporting for subsequent treatment. The resulting layer 778 passes to the jet-treating apparatus, described below, for conversion to a nonwoven fabric. Apparatus for con tinuous drying and windup of the fabric is also indicated.

The layer-forming apparatus processes a given weight of material at a relatively slow rate, whereas the jettreating apparatus is capable of high speed operation. Increasing the speed of the layer-forming apparatus will result in a lighter weight layer. Therefore, it may be desirable to provide more than one layer-forming apparatus, combine the layers, and feed the combination of layers to the jet-treating apparatus. When the layers are of the same material, the treatment will produce a homogeneous product with no evidence of lamination. However, different types of layers can be combined for special purposes and they will be securely entangled together by the jet treatment.

The jet-treating apparatus shown has three treatment drums 790, 791 and 792. With this arrangement, the fabric formed on the first drum can be treated from the reverse face on the second drum and, if desired, given an additional treatment on the third drum, all in a continuous, uninterrupted operation. However, one or two of the drums can be by-passed when treatment thereon is not desired. As shown in FIGURE 7, the layer 778 travels continuously from the layer-forming apparatus to the first treatment drum 790. A guide roll 793 is shown, and additional guiding or supporting means may be provided in order to feed the layer smoothly onto the cylindrical surface of the drum. The drum rotates counterclockwise and carries the layer beneath a plurality of jet-treatment manifolds 794. The fabric produced then leaves the first drum and travels over a series of guide rolls 795 to the second treatment drum 791. This drum rotates clockwise and the fabric is fed onto it so that the previously treated face is next to the cylindrical surface of the drum. The fabric is carried beneath a plurality of jet-treatment manifolds 796 to treat the face of the fabric opposite to that previously treated. From the second drum the fabric is guided by a series of rolls 797 to the third treatment drum 792. This drum rotates counter-clockwise to carry the fabric beneath a plurality of jet-treatment manifolds 798. This completes the treatment with liquid jets and the fabric leaves the drum at guide roll 799.

The jet-treated fabric passes to a wringer 700 to partially remove the treating liquid. The fabric is guided by a series of rolls 701 to conventional drying cans or drums 702, which are heated to dry the fabric. The dry fabric proceeds to a conventional type of fabric windup 703.

The used treating liquid falls into a drip tank 705 and is recovered, except for a small amount carried in the fabric to the drying apparatus. The liquid is withdrawn from the tank through drain 706, is passed through a filter 707 to remove any fibers or foreign matter, and continues through pipe 708 to pump 709. A multiple-piston, positive-displacement pump powered by an electric motor 710 is preferable. A multiple-stage centrifugal pump can be used, but is less efiicient for pumping large volumes of liquid at high pressure. Since a piston pump causes pulsation surges, even when there are five or more pistons, a pulsation dampener 711 is provided in high pressure pump line 712. A conventional fluid-filled, in-line pulsation dampener is preferable in large scale operation, instead of the gas-dampener shown in FIGURE 4, because of the simplicity and greater safety provided when high pressure liquid is supplied at a substantial rate. The treating liquid flows from dampener 711 to a second filter 713 designed to remove any remaining particles of material large enough to plug the jet orifices. A pleated woven screen which will remove any particles of larger than 25 microns in size is preferred. The filtered liquid then flows into a feed manifold 714 which supplies the jet manifolds 794, 796 and 798. Conventional pressure-control and highpressure-relief valves (not shown) should be provided to supply the liquid at the desired pressure with safety.

Further details of the jet treating apparatus are shown in FIGURE 8. The single treatment drum illustrated is similar to the third drum of FIGURE 7 and the elements are correspondingly numbered. The fibrous material for treatment may come directly from the layer-forming apparatus, without previous jet treatment. Layer 778 is guided by rolls 797 onto the cylindrical surface of the treatment drum 792, is carried under jet manifolds 798, leaves the drum at guide roll 799, passes through Wringer 700, and is guided by rolls 701 to drying apparatus.

The treatment drum is constructed so that the cylindrical surface contacting the fiber layer is a fine mesh screen or solid surface. A member which does not have sufficient rigidity, such as a woven wire screen, must be supported. A honeycomb support 115, made of thin sheet metal with about /s-inch cells and at least 1 inch in thickness, is preferred. The circular ends of the treatment drum rest on rollers 116.

The jet manifolds 798 are mounted on frame 117 which is supported on bearing blocks 118 at four corners of the frame. Drive means can be connected to the frame by means of an eccentric to impart a circular oscillation to the frame and the jet manifolds mounted thereon. The jet manifolds are mounted on the frame by adjustable means 119 and are supplied with high pressure liquid through flexible hoses 120, which are connected to high pressure manifold 714 by suitable fittings 121.

FIGURE 9 is an isometric view of a portion of jet manifold 798, shown at a larger scale and with the parts separated for clarity. Along the central axis of flat metal strip 122 are equally-spaced jet orifices 123. Above this jet strip is a perforated filter plate 124 which has the same outer dimensions as the jet strip but is curved upward along the central axis so that the plate is spaced away from the jet orifices. The plate is perforated with holes 125, which should not be larger than the jet orifices if intended to catch particles of foreign matter before they can plug the jet orifices. The holes are preferably smooth ly rounded and uniformly arranged along the curved portion of the plate to provide an even flow of liquid to the different jet orifices. A sufiicient number of holes to provide about 3.5 percent open area produces an even flow of liquid without excessive pressure drop through the filter plate. The manifold body 126 has an undercut portion 127, for receiving the filter plate and jet strip, and has a slot 128 which forms a liquid chamber above the filter plate. Fitting 129 connects to flexible hose for introducing high pressure liquid into the chamber. A heavy retainer plate 130 is secured to the manifold body by bolts 131 to hold the filter plate and jet strip in place in undercut portion 127 with a liquid-tight seal. A slit 132 extends along the central axis of the retainer plate to expose the jet orifices 123.

PROCESS The mechanism of the process of this invention appears to be one in which the fibers of the sheet material are caused to move, intertwine, or interlace with other fibers under the influence of high velocity liquid streams. The behavior of the fibers is best described with reference to FIGURES 10, 11 and 12. FIGURE 10 shows a crosssection of a substantially unmodified batt of randomly arrayed fibers. It may be seen that carded and crosslapped filaments are arrayed in strata in which individual filaments are more or less parallel to the horizontal; the filaments are not parallel to each other but are dispersed more or less randomly. The approximate boundaries of the strata are defined by horizontal lines; these lines are not intended to depict staple fibers. The behavoir of one filament 170, marked with Xs along its length, is reviewed below.

In FIGURE 10, the filament 170 is seen to lie in the unmodified batt near the top of the batt and generally parallel to the plane of the batt. Liquid streams 138 are shown impinging on the top face of the batt.

FIGURE 11 shows the same batt after a short duration exposure to a high velocity liquid stream 138. In FIGURE 11, the filament 170 is seen to be driven substantially through the entire thickness of the batt at two points 171 and 172. The liquid streams penetrate the full thickness of the batt and impinge upon the backing. The primary function of the backing is to serve as a support for the batt material. Preferably a screen or similar material, which will permit the flow of water therethrough, is used. As it impinges on the backing, the stream or a portion thereof may be deflected, i.e., proceed in a generally horizontal direction or in the plane of the batt, carrying filaments therewith as shown by the loop in the filament at point 173. At this stage, the filament 170 is rather thoroughly entangled with its neighbors and vice versa. In effect, the various strata of the batt are sewn or stitched" together by the migration and interentangling of the fibers.

FIGURE 12 shows the same batt after it has been manually turned over and treated with high velocity liquid streams on its reverse side. It is seen that further interentanglement and intertwining of the filaments occurs in random fashion so that the batt becomes highly coherent in the region in which it is treated by the liquid streams. Examination of the treated batt reveals that some filaments essentially pierce the batt at several different cations, thus acting as randomly dispersed sewing threads. The treated batt generally exhibits considerable tensile strength on a three-dimensional scale and also shows a markedly increased resistance to surface abrasion.

While the description just given does not specify the area of the lbatt that was treated, obviously any area up to and including the total area may be treated depending on the type of end product desired.

In order to obtain the high-strength nonwoven fabrics of the present invention, it is essential that the initial material be subjected to the action of streams of a noncompressible fluid at sufiiciently high energy flux and for a suflicient amount of treatment to entangle the fibers thereof. The energy flux EF of the streams will depend upon the jet device used, the pressure of the liquid supplied to the jet orifice, and the orifice-to web spacing during treatment. The liquid initially forms a solid stream, i.e., an unbroken, homogeneous liquid stream. The initial energy flux, in foot-poundals per square inch per second, is readily calculated by the formula,

EF =77 PG/a where:

P=the liquid pressure in p.s.i.g.

G=the volumetric flow of the stream in cu.ft./minute,

and

a=the initial cross-sectional area of the stream in square inches.

The value of G for use in the above formula can be obtained by measuring the fiow rate of the stream. The initial cross-sectional area a, which is inside the jet device, can be determined by measuring the actual orifice area and multiplying by the discharge coefiicient (usually 0.64), or it can be calculated from measured fiow rates. Since the area a corresponds to solid stream flow, the above formula gives the maximum value of energy flux which can be obtained at the pressure and flow rate used. The energy flux will usually decrease rapidly as the stream travels away from the orifice, even when using carefully shaped orifices. The stream diverges to an area A just prior to impact against the Web and the kinetic energy of the stream is spread over this larger area. The crosssectional area A can be estimated from photographs of the stream with the web removed, or can be measured with micrometer probes. The energy flux is then equal to the initial energy flux times the stream density ratio (a/A Therefore, the formula for energy flux at the web being treated is:

EF =77 PG/A ft.-poundals/in. sec.

The value of A increases with the orifice-to-web spacing and, at a given treatment distance, the value depends upon the jet device and the liquid supply pressure used. A pressure of 200 p.s.i.g. can provide sufficient energy flux for several inches when using a highly efiicient jet device, e.g., as in Examples I, II, IIIB, IV-B, VB, VI and VII. With other jet devices, the energy flux of a stream may become too low in a relatively short distance even when using higher pressures, due to the stream breaking up and losing its columnar form. When this occurs, there is a sudden increase in the value of A and the energy flux drops rapidly. Since the stream may become less stable when higher pressures are used, the energy flux at a given treatment distance may actually decrease when the jet orifice pressure is increased to provide a higher initial energy flux (PG/a). Some stream density (a/A) and energy flux determinations for water streams from drilledtube orifice manifolds, of types used in Examples IIIA, IV-A and V-A are given in the following tables:

% inch inch 1.5 inch For 3 Mil Orifice Diameter:

200 p.s.i.g.:

Stream Density (a/A) 0. 0758 0. 0625 0. 0545 Energy flux 85, 000 70, 000 61, 000 500 p.s.i.g.:

Stream density (alA) 0. 0758 0. 0522 0. 0405 Energy flux 330, 000 230, 000 180, 000 1,000 p.s.i.g.:

Stream density (alA) 0.0758 0. 0441 0. 0349 Energy flux 040, 000 540, 000 430, 000 1,500 p.s.i.g.:

Stream density (a/A) 0. 0758 (J. 0405 0. 0304 Energy flux l, 720, 000 920, 000 000, 000 For 5 Mil Orifice Diameter:

200 p.s.i.g.:

Stream density (a/A) 0. 241 0. 103 0. 0785 Energy flux 270, 000 115, 000 88, 000 500 p.s.i.g.:

Stream density (a/A) 0. 214 0.0763 0.0565 Energy flux 930, 000 330, 000 250, 000 1,000 p.s.i.g.:

Stream density (a/A). 0. 190 0. 0595 0. 0108 Energy flux 2, 340, 000 730, 000 130, 000 For 7 Mil Orifice Diameter:

200 p.s.i.g.:

Stream density (aiA) 0.357 0. 0. 0563 Energy flux 400, 000 140, 000 63, 000 500 p.s.i.g.:

Stream density (a/A) 0.281 0. 097 0. 037 Energy flux l, 225, 000 421, 000 162, 000 1,000 p.s.i.g.:

Stream density (a/A) 0. 236 0. 079 0. 0196 Energy flux 2, 910, 000 972, 000 242, 000 1,500 p.s.i.g.:

Stream density (a/A) 0. 236 O. 0645 0. 0125 Energy flux 5, 350, 000 1, 460, 000 283, 000

The high strength, nonwoven fabrics of the present invention can be produced by treating the web with streams of water jetted at sufficiently high pressure and having an energy flux EF of at least 23,000 ft.-poundals per inch second. Such streams are preferably obtained by propelling a suitable liquid, such as water, at high pressure through small-diameter orifices under conditions such that the emerging streams remain essentially columnar at least until they strike the initial material. By essentially columnar is meant that the streams have a total diverg- 13 ence angle of not greater than about degrees. Particularly, strong and surface-stable fabrics are obtained with high-pressure liquid streams having an angle of divergence of less than about 3 degrees.

The amount of treatment must be sufficient and is measured by energy expended per pound of fabric produced. The energy E expended during one passage under a manifold in the preparation of a given nonwoven fabric, in horsepower-hours per pound of fabric, may be calculated from the formula:

E =O.125 (YPG/sb) where:

Y=number of orifices per linear inch of manifold,

P: pressure of liquid in the manifold in p.s.i.g.,

G=volumetric flow in cu.ft./ min./ orifice,

s=speed of passage of the web under the streams, in

ft./ min., and

b=the weight of the fabric produced, in oz./yd.

The total amount of energy expended in treating the web is the sum of the individual energy values for each pass under each manifold, if there is more than one.

When treating fibrous material with streams of water impinged on the material at an energy flux EF of at least 23,000 ft.-poundals/in. sec., jet-track-patterned entangled nonwoven fabrics can be prepared at expenditures of energy of at least about 0.1 HP-hr./lb. of fabric. At any given set of processing conditions, surface stability of the nonwoven fabric obtained (i.e., the resistance of the fabric to surface pilling and fuzzing) can be improved by increasing the total amount of energy -E used in preparing the fabric. There is, however, a maximum energy of about 5-10 HP-hr./lb. beyond which little additional surface stability is developed. For products with sufficient surface stability to withstand repeated launderings, such as might be required for certain apparel and other uses, an energy flux EF of at least 100,000 ft.-poundals/in. sec. and an energy E greater than 1 HP-hr./lb. of fabric are preferred.

The process of the present invention may be used to produce entangled nonwoven fabrics from any type of loose fibrous web, batt, or sheet. The ease with which a given web can be entangled is dependent upon many factors, and process conditions may be chosen accordingly. Fiber mobility also has a bearing on the ease with which a web can be processed. Factors which influence fiber mobility include, for example, the density, modulus stiffness, surface-friction properties, denier, crimp and/or length of the fibers in the web. In general, fibers which are highly wettable, or have a high degree of crimp, or have a low modulus or low denier, can also be processed more readily.

If desired, the initial fibers or layer may be treated first with a wetting agent or other surface agent to increase the ease of processing, or such agents may be included in the liquid stream.

Depending upon the nature of the initial fibrous layer and the nonwoven fabric to be produced, the energy flux exerted by the liquid streams may be adjusted as desired by varying the size of the orifices from which the streams emerge, the pressure at which the liquid is delivered, the distance the web is separated from the orifices, and the type of orifice. Other process variables, which may be manipulated in order to achieve the desired nonwoven fabric include the speed of the fibrous sheet, the number of times it is passed into the path of the streams, and/or the directions in which it is passed into the path of the streams.

Wherever the columnar streams act on the sheet, individual fibers in the sheet are forced into an interentangled relationship with each other in all dimensions of the sheet. A single stream, or a multiplicity of streams spaced a preselected distance apart, depending on the effect desired, may be applied continuously or intermittently to the sheet material in a direction perpendicular or oblique to its surface. The fibrous sheet material may be treated along its lengthwise direction and/or transversely and/or obliquely thereto. The fibrous sheet material may be treated from one side only or from both sides, the latter being carried out in successive steps.

The individual streams must be of sufficient fineness to produce the desired filament interentanglement without permanently separating groups of fibers, i.e., without forming openings in the sheet. In general, the streams are formed by orifices of 2 to 15 mils in diameter (preferably less than 10 mils). Orifice size may also be varied depending on the material to be treated and the effect desired. In general, for treating loose fibrous batts and the like it is preferred to vary the orifice size according to the basis weight of the sheet and the denier of the fibers therein. Preferably small diameter orifices are used for low basis weight, low denier materials, while larger orifices are used as the weight or denier increases.

During treatment, the fibrous web can be supported by a screen or other apertured support or a solid surface such as a flat plate or a bar. If a screen or similar apertured support is used, it is preferably selected in accordance with conditions illustrated in the examples. As shown in the examples, jet-track-patterned nonwoven fabrics and substantially nonpatterned nonwoven fabrics can be prepared on a variety of screens by adjusting these variables or by treating the web while supported against a solid plate or bar.

Example I This example illustrates the treatment of different initial materials with streams of water issuing from 0.015- inch orifices to prepare nonwoven fabrics having seams arranged in a crisscross pattern.

A 2.5 oz./yd. web of randomly disposed fibers is prepared by a random web air-laying technique from 3.7 denier per fiber (d.p.f.), Australian tops wool. By assembling layers of this web, a series of initial materials of 5, 10 and 20 oz./yd. is prepared. A similar series of initial materials is prepared from a blend of 50% by weight of 1.5 denier per fiber (d.p.f.), 1.5-inch long, acrylic fibers and 50% by weight of 1.5 denier per fiber, 0.25-inch long rayon fibers.

Using apparatus of the type shown in FIGURE 4, each initial material is treated with essentially columnar streams of water issuing from orifices drilled in line in a manifold at a spacing of 5 orifices per inch. Special care is taken in the cleaning and boring of the orifices to get as sharp an entry into the orifice as possible to minimize any breaking up of the stream issuing from the orifice. Uniformity of water distribution to the orifices is facilitated by use of a cylindrical filter which is mounted coaxially within the manifold assembly, spaced from the walls thereof, and extends over the full length of the assembly. The filter is a fine mesh wire screen x 80 wires per inch and 36% open area).

The initial material is placed on a support screen and is passed under the streams of water so that they traverse one major direction of the initial material, which is then removed from the screen, turned over, replaced on the support screen and treated in the direction transverse to the first treatment. Sufiicient passes under the streams are used to provide for treating each initial material with an energy of approximately 2 HP-hr./ lb. of initial material, the passes being equally divided between the two directions of treatment. During passage under the streams, the initial material is moved to about 2 yds./min. and is spaced about 1 inch from the orifices. The support screen is either a 20 mesh (20 x 20 wires/inch, 29% open area) or an 80 mesh (80 x 80 wires/inch, 30% open 15 area) woven wire screen. Treatment conditions for each initial material are summarized in Table I.

The products obtained have criss-cross seam-like lines of fiber entanglement corresponding to the lines of passage of the liquid streams and spaced accordingly (i.e.,

size and spacing. During treatment the web is placed on a woven wire support screen of either 20 mesh (20 x 20 wires per inch, 29% open area) or 80 mesh (80 x 80 wires/inch, 36% open area), which screen serves to support the web and does not influence the final pattern of 5 5 seams/inch) They are strong and fabric 1ike in the nonwoven fabric because the et streams are advanced thetics. When tested in the absence of any added bonding {Speatedly alolgg 3 path; to glve a Pg fi i agent or further bonding method, the products have an 6 Same i er mes t ere are on ces per mc t n 1 t 1 t t th 0 d Treatment involves (l) passlng. the supported web under an a gemen compe eneis 0 er an an 10 the streams of water so that they traverse one major fintallglement frequency f greater than as seen 111 direction of the material for a given number of passes, Table Both faces of a representative P p F providing one-half of the total energy expended in the 1n Table I, are shown in the photographs of FIGURES 13 treatment, each pass following the same path so that the and 14 and at 10X in FIGURES 15 and 16. streams strike the web in the same place during each TABLE I Initial Material Processing Conditions Product Properties Strip Energy Flux Energy Tensile Entangle- Entangle- Support Orifice of Streams Total Expended Water Strength ment Frement Com- Sample Weight. Screen Size (ft.-pounda1s/ No. of (HP-hr./- Pressure (1b./in)./- quency pleteness (3) Code Composition (ca/yd?) (mesh) (inch) in. sec.) Passes lb.) (p.s.i.g.) (en/yd?) (No/in.)

A Acrylic/rayon .5 0. 015 1,100,000 64 2 200 1.3 23 0.53 B d 5 so 0. 015 1, 100, 000 67 2 200 1. 7 19 0. 45 5 s0 0. 015 4, 400, 000 18 2 500 3. 0 39 0. 02 10 20 0. 015 1, 100,000 128 2 200 1. 3 22 0. 54 5 s0 0. 015 1, 100, 000 67 2 200 1. 9 21 0. 88 1o 20 0. 015 1, 100, 000 12s 2 200 1. 5 19 0.79 20 20 0. 015 1, 100. 000 25s 2 200 1.1 20 0.88

Example II pass, and (2) turning the web over, replacing it on the This example illustrates the synergistic effect obtained when using small orifices, closely spaced and using water pressures greater than 200 p.s.i.g.

A series of samples, coded A through N, is prepared using as initial material a 2.5 oz./yd. web of randomly screen, and repeating the first treatment in a direction 90 thereto. Sufiicient total passes under the streams are used to provide for total treatment of the web with an energy of approximately 2 HP-hr./lb. of web. During treatment, the web and screen support are moved on a conveyor belt at a speed of 2 yds./min. and the web is spaced about disposed fibers prepared by a random web air-laying technique. Each web is prepared from a 50 blend, by one ll'lCh from the orifices. Treatment conditions are weight, of 1.5-inch long, 1.5 denier per filament acrylic summarized in Table II.

TABLE II Strip Tensile Total Energy Energy Flux Support Strength Orifice Orifices Pressure Passes (HP-hrJ- (ft.-poundals Screen (lbJin. per Size (in.) per Inch (p.s.1.g.) (Nd) lb.) per infi-sec.) (mesh) ozJydfi) 0. 007 20 500 s 2 4. 4x10 20 s. 92 0. 007 20 500 s 2 4. 4x10 3. 38 0. 007 20 500 s 2 4. 4x10 20 2. 88 0.007 20 200 32 2 1. 1x10 80 2. 0. 007 20 200 32 2 1. 1X10 20 2. 47 0. 007 20 200 32 2 1. 1x10 30 1. 95 0. 030 5 200 s 2 1. 1x10 20 1. 10 0. 030 5 200 s 2 1. 1x10 20 0*) 0. 007 20 54 2 0. 4x10 20 0. s5 0. 007 20 100 64 2 0. 4x10 20 0. 030 5 100 16 2 0. 4x10 20 0. 7e 0. 007 5 100 12s 2 0. 4x10 20 0. l6 0. 030 5 500 2 2 4. 4x10 20 (*1 0. 030 5 500 2 2 4. 4x10 80 *Line-patterned product not achieved since particular screen/orifice size/pressure/web combinations led to bubbling, washing away, or blowing apart of the web.

fibers and 0.25-inch long, 1.5 denier per filament rayon fibers. For each sample, the web is supported on a screen and treated by passing it back and forth under essentially columnar streams of water issuing from orifices drilled in line in a manifold to thereby produce in the web a series of lines of fiber entanglement corresponding in number to the number of orifices in the manifold. The orifices are carefully cleaned and bored to get as sharp an entry into the orifice as possible to minimize any breaking up of the stream issuing from the orifice. When using the manifolds having orifices spaced 5/ inch, uniformity of water distribution to the orifices is facilitated by use of a cylindrical filter which is mounted coaxially within the manifold assembly, spaced from the walls thereof, and extends over the full length of the assembly. The filter is a fine-mesh wire screen (80 X 80 wires per inch and 36% open area). A manifold of the type shown in FIGURE 9 is used when the orifices are spaced 20/ inch. Either arrangement is satisfactory regardless of orifice Example 111 (A) In operating the process of this invention, velocity and consequently momentum of the discrete column of fluid contacting the fibers must be sufficiently high as to physically drive the fibers into an interentangled relationship with other fibers. The actual velocity required is dependent on the nature of the fibrous sheet to be treated and on the degree of fiber interentanglement desired. Velocity may be adjusted to any desired level, for example, by varying the pressure on the liquid in FIGURE 1. In Table III, the effect of varying the pressure and/ or the orifice size is shown. In each case, the starting material is a continuous filament web. The Web is placed on a 30-mesh screen and treated using apparatus of the type shown in FIGURE 4. The web is subjected to two passes, one transverse to the other, on each side of the web and is passed so as to just contact the orifices.

TABLE III Strip Tensile Orifice Orifice Strength Elonga- Modulus Drape (in.) Spacing Pressure (lbs/in?) tion (per- (lbs./in. Flex. (No./in.) (p.s.i.g.) (oz ./yd. cent) (oz./yd. (cm.)

Properties of untreated web for comparsion- 0. 14 53 0.07 1.6

(B) Additional Samples are prepared using another initial web. The web is composed of randomly disposed, crimped, continuous, bicomponent filaments composed of equal weights of polyhexamethylene adipamide and a copolyamide of hexamethylene adipamide and hexamethylene sebacamide units (80/ 20). Filament denier is 2.6 and filament tenacity is 2.1 grams per denier. Specific processing conditions are given in Table IV. For each sample, a web is placed on a woven wire screen, which serves merely to support the web during treatment. The supported web is passed under essentially columnar streams of water from sharp-edged orifices arranged in line in a manifold at the given spacing per inch. The orifices are carefully cleaned and bored to get as sharp an entry into the orifice as possible to minimize any breaking up of the stream issuing from the orifice. Uniformity of water distribution to the orifices is facilitated by use of a manifold of the type shown in FIGURE 9. Unless otherwise indicated, each web is passed under the streams two times, one pass at right angles to the other, and is then turned over on the screen and again given 2 passes, one at right angles to the other, for a total of 4 passes. During treatment the Web is spaced about 1 inch from the orifices, and is moved under the orifices on a conveyor belt, at the speeds indicated in Table IV.

All of the products are characterized by the presence of lines of entanglement when viewed from a least one surface of the product, corresponding in number to the number of orifices per inch in the treatment manifold, i.e., 20 or 40 lines of entanglement per inch. These entangled regions are present at suflicient frequency to provide strength and coherency to the nonwoven fabrics as may be seen from the tensile strength, ranging from 2.9 to 6.1 lbs/in. per oz./yd. and entanglement completeness values '6 ranging from 0.94 to 1.3. Entanglement frequency values T range from 20 to 217, indicating adequate to excellent surface stability. The products of this invention as shown in Table IV were all prepared at energy flux values greater than 12 10 ft.-poundals/in. sec. and energy values greater than 0.12 HP-hr./ lb. of fabric.

TABLE IV Orifice Orifice Water Support Energy Flux Diameter Spacing Pressure Belt Speed Screen (ft.-poundals Energy Sample (in. (No/111.) (p.s.i.g.) (yds./min.) (mesh) 11 per in. sec.) (HP-hr.llb.)

A 0. 0025 40 2, 000 20 30 x10 0, 12 B 0. 0025 2, 000 10 30 35X10 0. 29 O 0. 0025 40 2, 000 5 30 35x10 0. D 0. 005 40 2, 000 20 30 35X10 0. 51 E 0. 007 20 2, 000 21 30 35X10 0. 35 F 0. 007 20 2, 000 10. 6 30 35X10 0. 61 G 0. 007 20 2, 000 5. 35 30 35X10 04 H 0. 007 20 2, 000 40 30 x10 0. 22 I 0 0. 007 20 2, 000 21 30 35X10 0 16 J 0. 007 20 2, 000 11 30 35 (10 0 51 K 0. 007 20 2, 000 5. 5 30 35X10 1. 02 L- 0. 007 20 2, 000 20 30 35X10 0. 39 M 0. 007 20 2, 000 10 30 35x10 0. 86 N 0. 007 20 1, 000 20 30 12 10 0 14 Strip Entangle- Entangle- Tensile 5% Secant ment Comment Fre- Test Direc- Strength Modulus pleteness quency Web Weight tion (MD (lb./in Elongation (1b./in.)/ Sample (5 f (om/yd?) or XD) b (oz./yd (percent) (ozJydfi) A 1. 2 29 3. 61 MD 5. 86 201. 6 1. 12 XD 5. 20 213. 0 1. 27 B 1. 2 20 2. 96 MD 5. 23 179. 5 0. 97 XD 4. 34 217. 5 0. 79 C 1. 0 34 2. 63 MD 5. 34 169 1. 48

XD 4. 64 3. 33 MD 5. 98 XD 4. 13 4. 66 MD 4. 48 4. 50 MD 5. 38 5. 94 MD 3. 96 3. 83 MD 2. 91 5. 0 MD 4. 2 6. 1 MD 5. 5 6. 1 MD 5. 5 4. 41 MD 5. 69 D 4. 73 3. 93 D 6. 07 XD 4. 28 4. 14 MD 4. 58

Only tested in MD.

1 9 Example IV (A) In operating the process of this invention, the fibrous sheet material is preferably treated while in contact with or fairly close to the orifice. As the distance from the orifice increases, passage of the liquid through the air causes turbulence and/or a breaking up of the columnar flow which reduces the extent or intensity of fiber interentanglement obtainable. This is illustrated in the table below with respect to treatment of a continuous filament web, using drilled-tube orifices of the type discussed prior to the examples in connection with the table of energy flux values, and a water pressure of 2000 p.s.i.g. Using tenacity as an indication of the extent of fiber interentanglement, it is observed from the table that the extent of fiber interentanglement generally decreases as the distance from the orifice increases. All other factors being equal, the extent of fiber interentanglement decreases as the pressure decreases.

to one another have lines of entanglement in 2 major directions of the fabric. The presence of lines of entanglement at these frequencies, i.e., 20 or 40/inch, provides good strength and coherence as may be seen from the following summary of the properties of the nonwovens:

Tensile strength: 6 to 8.5 (lb./in.)/(oz./yd. Entanglement completeness 'c: 0.85 to 1.0

Entanglement frequency T: 16 to 39 Energy (HP-hr./lb.): 0.31 to 1.47

Energy flux (fL-poundals/in. sec): 4.4)(10 to l0 From a comparison of Samples A and B With Sample C and of Samples H and I with Samples I and K, it may be seen that for a given set of conditions, including the particular manifold, initial web, etc., treatment efficiency decreases as the web-to-orifice spacing increases. Thus for the particular conditions of these samples, spacing of 5.6 inches was enough to break up the stream (B) In a similar experiment, a series of samples is prepared using a web of continuous, polyethylene terephthalate filaments having a filament denier of 1.3 and a filand make it sufficiently turbulent to prevent entanglement of the web in lines corresponding to the number of orifices.

TABLE V Orifice Orifice Web-Orifice Water Belt Support Diameter Spacing Spacing Pressure No. of Speed Screen Sample (in,) {No.lin.) (in.) (p.s.i.g.) Passes (yds./min.) (mesh) a A 0. 0025 1 2. 83 8 O B O. 0025 40 1 0. 71 80 c 0. 0025 40 5. 6 0. 71 30 D 0. 005 20 1 2, 000 s t 12. 5 30 E 0.005 20 1 500 e 4 1. 4 30 F 0. 001' 20 1 1, 000 e 4 7. 5 30 G 0.007 20 1 500 e 4 2. 30 H 0. 007 20 1 11. 4 I. 0. 007 20 1 2. 86 80 J. 0. 007 20 5. 6 11. 4 80 K 0. 007 20 5. 6 2. 86 80 Strip Strip Tensile Tensile Strength Strength Energy Flux Entanglement Entangle- Web MD) b (XD b (it. poundals Energy Completeness ment Fre- Weight (lb.lin.)/ (lb./in.)/

Sample per in. sec.) (HP-hrs./lb.) (E) quency (i) (on/yd?) (on/yd?) (oz/yd?) asxlc 2. 28 2. s

a 80 mesh=80 x 80 wires/in, 30% open area. 30 mesh=30 x 30 wires/in, 40% open area.

MD tested in direction of lines of entanglement. XD tested 90 to MD.

e Complete treatment includes: 1 pass, 500 p.s.i.g., using 16 x 18 mesh, 71% open area top screen. Sample turned overl pass, 2,000 p.s.i.g., no top screen.

Complete treatment includes: 1 pass, 500 p.s.i.g., using 16 x 18 mesh, 71% open area top screen. Sample turned over-1 pass, 2,000 p.s.i.g., using same top screen; 1 pass, 2,000 p.s.i.g., no top screen.

e 2 passes, 1 at 90 to other; sample turned over; 2 passes, 1 at 90 to other.

1 Sample nonuniform; properties could not be determined.

ament tenacity of 3.6 grams per denier, Processing conditions are as in Example III-B unless otherwise indicated in Table V. Products A, B and D through I are characterized by the presence of lines of entanglement corresponding in number to the number of orifices per inch in the treatment manifold, i.e., 20 or 40 lines of entanglement per inch. Products given 1 pass have entanglement lines in one direction only. Those given passes at 90 Example V (A) The extent of fiber interentanglement obtainable at any given pressure can be increased by increasing the number of passes. The following table illustrates the etfect of repeated passes on a continuous filament web. Apparatus of the type shown in FIGURE 4 is used. The sample is placed on a 30-mesh screen and is passed so as to just contact the 0.0028-inch orifices supplied with 21 water at 1500 lbs./in. Each treatment consists of two passes, one transverse to the other, per side of the web. There are 40 orifices per inch in the manifold.

The initial material is a web of randomly disposed fibers prepared by random web air laying technique. The web contains 50% by weight of 1.5 inch, 1.5 denier acrylic fibers and 50% of 0.25 inch, 1.5 denier acrylic fibers, and weighs about 3 oz./yd. The web is treated Tesnllslillle) with essentially columnar streams of water issuing from Strength Modulus Drape 0.007-inch diameter orifices, drilled in a line in a mani- Treatments (lbs/i112] Elong. (lbs-ling! Flexfold at a frequency of 20 orifices/inch. The web is held (sdes) (oz'lyd") (pecem) against the flat surface of a one-inch wide metal bar, 1% 2 g which is held stationary during treatment. The web is 1 spaced one inch from the orifices during treatment and is moved over the bar at a speed of 2 yards per minute. The streams of water strike the web and then the flat sur- Orifice ize may also be varied depending on the maface Of the bfll at about 90 to the flat surface. Th6 Web terial to be treated and the effect desired. In general, is passed under the streams once using a water pressure for treating loose fibrous batts and the like, it is preferred f 500 p- -i-gand Once using 1000 P- It is then to vary the orifice size according to the basis weight of turned over and passed once more under the streams, at the sheet and the denier of the fibers therein. Preferably, 1000 p.s.i.g. while held against the flat bar. Energy flux small diameter orifices (e.g., 0.0028 inch) are used for of the streams at 1000 p.s.i.g. is 12x10 ft. poundals/in. low basis weight, low denier materials, while larger orisec. and total energy expended in the treatment is 1.4 fices (e.g., 0.005 inch 01' 0.007 in h) are u as t HP.-hr./lb. All passes are done in one major direction of basis weight or denier increases. the web and the resulting nonwoven fabric has 20 lines of Additional Samples are P p using as initial entanglement per inch in one fabric direction, correspondmaterial Webs f the yp described in f pl ing to the number of orifices per inch. This provides good In treatlng the Webs, the number of Pf 1S vanefi from strength and stability as can be seen from the following 1 to 8. However, all repeat passes 1nvolve moving the Properties. web under the streams along the same path as the first pass so that the streams strike the web in the same place Stri tensile strength (lb./in.)/(oz./yd. during each pass. Other processing conditions are as in MD 4.6 Example II unless otherwise specified in Table VI. XD 3.4

The products obtained, as viewed from one fabric face, Elongation (percent): have lines of entanglement per inch in one maj r MD rection of the fabric. This provides good strength and X1) 7 stability in both directions of the fabric as may be seen 5% Sec-ant modulus 1b 2 from the properties in Table VI, wherein th following 35 MD 0.4 ranges are seen: XD 0.4 Strip tensile strength: 4.5 to 7.3 lb./in.)/(oz./yd. Entanglement completenefs 0 Entanglement completeness '6: 0.82 to 0.92 Entanglemer}? frequency f 22 Entanglement frequency T: 10 to 18 40 Surface Stablhty: Energy: 0.15 to 1.16 HP-hr./lb. P face Energy flux: 23 1O ft.-poundals/in. sec. Bottom face In general, for these webs, an energy of 0.15 is ade- Note: quate to provide a strong, well-entangled product. In- MD: tested in direction of lines of entanglement creasing the energy to 0.26 or more, all other conditions 4 XD t t d 90 t MD remaining unchanged improves the surface stability of the nonwoven fabric as shown by the increased entanglement Surface stability is determined as described near the frequency 7 values obtained in Samples B, C and D, end of the specification.

TABLE VI Strip Test Di- Tensile 5% Secant Energy Flux Energy Entangle Entangle' Web rection Strength Elonga- Modulus No.01 (ft.-p0unda.ls I-Ip-hrJ ment 3- ment E- Weight (MD or (lb./in.)/- tion (per- (lb./in.)/ Sample Passes per in. sec.) lb.) pleteness (c) quency (i) (om/yd?) XD) e (oz./yd. cent) (oz./yd.

A 1 23x10 0.15 0. 87 10 2.47 MD 4.48 81.9 2.04 XD 6.80 81.5 4.67 B 2 23x10 0.26 0.84 18 2.90 MD 6.67 101.2 3.00 XD 7.17 94.0 3.58 C 4 23x10 0.61 0.82 17 2.46 MD 6.55 91.8 4.20 KB 6.84 83.4 4.63 D 8 28 10 1.16 0.92 17 2.60 MD 7.13 81.0 5. 84 XD 7. 30 81.1 6.12

a MD is tested in direction of lines of entanglement; XD is tested 90 to MD.

Example VI This example illustrates preparation of a nonwoven fabric having 20 lines of entanglement per inch, using a flat bar to support the web during treatment.

Example VII This example illustrates preparation of a nonpatterned nonwoven fabric using a flat, solid support plate for the web.

The initial material is a 2.9 oz./yd. web of randomly disposed staple fibers, prepared by a random web airlaying technique and consists of 50% by weight of 1.5 inch, 1.5 denier per filament (d.p.f.), acrylic fibers and 50% by weight of 0.25 inch, 1.5 d.p.f. rayon fibers. The web is placed on a fiat metal plate and is passed under essentially columnar streams of water issuing from 0.007- inch diameter orifices drilled in a single line, 21 inches long, on 0.05 inch centers (ZO/inch). During treatment, the plate is positioned so that the streams are directed against it at about 90 to its fiat surface. Water temperature during treatment is about 60 C. The orifice manifold is oscillated at approximately 300 oscillations er minute; diameter of oscillation path is 0.5 inch. The web, supported on the plate, is passed under the streams at a speed of 2 yd./min. and spaced approximately 0.5 inch from the orifices. A coarse mesh screen is placed over the web during the entire treatment to restrain the Web. Processing is as follows:

1 pass using 500 p.s.i.g. pressure, 2 passes using 1000 p.s.i.g. pressure, sample turned over on the plate, and 2 passes using 1000 p.s.i.g. pressure. All passes are done in one major direction of the web. Energy flux of the streams is 12 10 ft.-poundals/inch sec. and total energy expended is 2.2 HP-hr./ lb. Properties of the final fabric are as follows:

Weight (oz./yd. 2.3 Strip tensile strength (lb./in.)/ (oz./yd.

XD 3 4 Elongation (percent):

XD 82 Entanglement completeness To) 0.7 Entanglement frequency G) 43 Surface stability (both faces) 3.8

Note:

MD=tested in one major direction XD=tested 90 to MD Surface stability is determined as described near the end of the specification.

As can be seen from the foregoing discussion and the examples, the process of this invention offers a high speed economical route to the production of a wide variety of textile products. In order to obtain the high degree of fiber interentanglement which characterizes the products of this invention, the starting material is acted upon by discrete columnar streams of liquid moving at high energy flux.

The fluid must be a liquid, since the stream must be capable of maintaining its identity as a discrete column for a finite distance beyond its point of emergence from the orifice. Compressible fluids, such as air, nitrogen, or other gases, which diffuse rapidly upon emerging from a nozzle orifice, are not effective. The results obtained by treatment with water and nitrogen are compared in the following example.

Example VIII A loose web consisting of randomly disposed continuous filaments is used as the starting material. Using apparatus of the type shown in FIGURE 4, a sample of the web is placed on a 30-mesh screen and passed in contact with 0.0028-inch orifices on 0.025-inch centers (40 orifices/inch) supplied with water at 2000 p.s.i.g. pressure. Two passes are used, one transverse to the other, on each side of the web. The web is removed, dried and examined. The loose web is observed to have been converted into a stable coherent non-woven fabric. A second sample is similarly treated except that 0.007-inch orifices on 0.050- inch (20 orifices per inch) centers are used and the sample is placed on a 30-mesh screen. Properties of the untreated and treated webs are given in the following table:

The marked increase in tensile strength of the watertreated samples shows that a high degree of fiber interentanglement has occurred.

The above two experiments are then repeated on additional samples of the web under identical conditions except that nitrogen at 2000 p.s.i.g. pressure is used instead of water. The nitrogen-treated samples are removed and examined. A few surface fibers appear to have been blown around but no other visible eifect is noted. The strength of these samples is substantially unchanged from that of the untreated web.

The above experiments are then repeated using a staple fiber batt as the starting material. Again, treatment with the high velocity liquid streams is observed to interentangle the fibers whereas treatment with the gaseous streams has no effect.

In a final test in this series, a sample of the staple batt is first moistened with water and then subjected to the action of nitrogen from 0.007-inch orifices at 2000 p.s.i.g. pressure. No fiber interentanglement is observed.

Example IX This example illustrates the synergistic effect obtained by using small orifices, close spacing, and water pressures greater than 200 p.s.i.g., for making substantially nonpatterned products.

(A) A series of samples, coded A through Q, is prepared, using as initial material a 2.5 0z./yd. web of randomly-disposed fibers prepared by an air-laying technique. Each web is prepared from a 50/50 blend, by weight, 1.5 inches long, 1.5 denier per fiber acrylic fibers and 0.25 inch long, 1.5 denier per fiber rayon fibers. For preparation of each sample, the web is supported on a screen x 80 wires/ inch, 31% open area) and passed under the jet streams at 2 yards/minute. The total passes under the jet streams are listed in Table VII; half the passes are done with the streams contacting one side of the Web, after which the web is turned over on the screen and treated with the remaining number of passes under the streams. The streams are essentially columnar streams of 50 C. temperature water issuing from orifices drilled in line in a manifold which is oscillated at 300 r.p.rn.; the orifices being about one inch from the Web during treatment. The orifices are carefully cleaned and bored to get as sharp an entry into the orifice as possible to minimize any breaking up of the streams issuing from the orifice. When using manifolds having orifices spaced 5 per inch, uniform water distribution to the orifices is facilitated by use of a cylindrical filter which is mounted c-oaxially within the manifold assembly, spaced from the walls thereof, and extends over the full length of the assembly. The filter is a fine-mesh wire screen (80 x 80 wires/inch and 36% open area). A manifold of the type shown in FIGURE 9 is used when the orifices are spaced 20 per inch. Either arrangement is satisfactory regardless of orifice size and spacing. During treatment, sufficient total passes under the streams are used to provide for total treatment of the web with an energy of the order of 2 HP-hr./lb. of web. Actual treatment energies are iven in Table VII. During treatment, vacuum is employed under the support screen (13 inches of water). The support screen does not influence the final pattern of the nonwoven fabric because of its fine mesh in relation to the other conditions employed; a slight surface pattern corresponding to the oscillation pattern of the jets is seen in the final product; however, the product is smooth, dense and when viewed by transmitted light shows a sub- (B) In Table VIII, data for a similar set of products prepared using rayon fibers are shown. In Example IX-B, all process conditions are as shown in the table or as described for Example IX-A with the exception that the starting web is 100% rayon and has a nominal weight of stantially uniform distribution of fibers area-wise. The 2 oz./yd. for Samples A through M and 6 oz./yd. for treatment reorients fiber segments transversely with re- Samples N through V. For 2 oz./yd. webs of rayon, it is spect to the plane of the web, i.e., in the thickness direcseen from Table VIII that a tensile strength of about 2 tion of the web; these transversely disposed fiber seg- (lbs./in.)/(oz./yd. can be achieved at 200 p.s.i.g., when ments are substantially randomly distributed throughout 10 using the 0.007-inch diameter orifices spaced either 5 per the area of the fabric. inch or 20 per inch.

Samples A through G of Table VII show what happens From Samples A to D of Table VIII, the effect of varywhen pressure is varied for the indicated orifice size ing pressure when using 0.030-inch diameter orifices, (0.030-inch diameter orifice) and spacing (5 orifices per spaced 5 per inch, is shown. No products having satisfacinch). Thus, for this orifice and spacing, a pressure of tory appearance and texture are obtained. A tensile 100 p.s.i.g. yields products with tensile strength of about strength of 0.86 is obtained at 100 p.s.i.g., and of 1.48 at 0.7 (lb./in.)/(oz./yd. Strength increases to about 1.5 200 p.s.i.g.; increasing the pressure to 500 and 1000 (lbs./in.)/(oz./yd. at 200 p.s.i.g.; treatment at 1000 p.s.i.g. results in destruction of the sample. p.s.i.g. destroys the sample. All samples prepared with Samples E through G, when compared to A through these large jets and this spacing have neither a smooth D, show the effect of decreasing orifice size from 0.030 texture nor a nonpatterned appearance. to 0.007 inch in diameter, with spacing remaining at 5 From Samples H through L, the eifect of reducing per inch and the pressure being varied. All of the products orifice size, while keeping the same orifice spacing, can B through G are satisfactory from the appearance standbe seen. At 100 and 200 p.s.i.g., the smaller diameter point. The sample prepared with 0.007-inch diameter oriorifice (0.007 inch) gives weaker products than did the fices at 100 p.s.i.g. is weaker than that prepared with 0.030 inch diameter orifice. Unexpectedly, however, at 0.030-inch orifice at 100 p.s.i.g. However, at 200 p.s.i.g. 500 p.s.i.g., strengths obtained with the 0.007-inch diamthe reverse is true; increasing to 500 p.s.i.g. still further eter orifice are higher than with the 0.030-inch diameter increases the strength to 3.37 (lbs./in.)/(oz./yd. when orifices. In addition, the products made with the 0.007- 0.007-inch orifices are used, whereas 500 p.s.i.g. destroys inch diameter orifice at spacing of 5 per inch are satisthe web when 0.030-inch orifices are used. factory in terms of aesthetic properties, i.e., appearance Samples H through M, when compared to B through and texture. G, illustrate the effect of increasing the orifice frequency The effect of both reducing the orifice size to 0.007 inch from 5 to 20 orifices per inch. From Sample H vs. Sample and increasing the orifice frequency from 5 per inch to E, It 1s seen that merely increasing t q y for the 2 pgr inch can be Seen f Samples M through Q f 0.007- nch diameter orifice, at 100 p.s.i.g., does not result Table VII. At 100 and 200 p.s.i.g. the increased frequency "K Increased strfmgth- However when smfill dlametfil' does not yield greater tensile strength; however, as can be Close i and 200 to 1000 P- P seen from Samples P and Q, the most desirable products 2? (52mm 5 1. g? i s deslrable products from the standpoint of high strength and satisfactory ap- 8 mpg an aes 6 5 are 0 mm 40 With the 6 oz./yd. webs, the 0.030-mch diameter 01'1- pearance are achleved when all three conditions (small ter 0 I 8 o d h fices, spaced 5 per mch (Samples N-Q), do not yield satmm H c 056 an 1g pr essure) are isfactory products at 100 to 500 p.s.i.g.; 1000 p.s.i.g. deemployed; thus, at 500 p.s.i.g., w1th the 0.007-mch orlfices stroys the Web. spaced Per a stljength of ls achleved- Thls 15 In contrast, when 0.007-inch diameter orifices, spaced further lncleased y 8 to 1000 P- as Show}! by 20 per inch are used (Samples R-V), strong products Samplfi Q when a tenslle Strength of (3-4 lbs/in. per oz./yd. with desirable appearance can (oz/yd?) is reached. be obtained at 500 to 1000 p.s.i.g.

TABLE VII Stn'p Tensile Orifice Orlfices Pressure P22 35 E ergy v v ili bslrength Kwduct s ner oun a e Size (111.) per inch (p.s.i.g.) (No.) (HP-hr./1b.) per iufl-secJ (om/ ozll ycllg 56 0. 030 5 100 16 1. 9 386, 000 2. 0 0. 66 Ns 0. 030 5 100 16 1. a 386, 000 2. 13 0. 74 NS 0. 030 5 200 8 2. 1 1,090,000 2. 3 1. 4 NS 0. 030 5 200 8 2. 1 1, 090, 000 2. 36 1.6 Ns 0. 030 5 500 2 1.8 4 310,000 2.2 2.2 Ns 0. 030 5 500 4 2. 2 0, 000 3.65 2. 32 NS 0. 030 5 1, 000 2 4. 4 12,200,000 Ns 0. 007 5 100 25s 1. 4 386, 000 2. 21 0. 04 s 0. 007 5 100 144 0. 8 386, 000 2. 10 0. 02 s 0. 007 5 200 128 1. s 1, 090, 000 2. 37 1. 02 s 0. 007 5 500 64 3. 7 4, 310, 000 2. 27 2. 92 s 0. 007 5 500 04 3. 6 4, 310, 000 2. 35 3. 18 S 0. 007 20 100 70 1. 4 386, 000 2. 35 0. 06 s 0. 007 20 200 40 2. 3 1, 090, 000 2. 2s 0. 23 s 0. 007 20 200 40 2. 1 1, 090, 000 2. 0. 22 s 0. 007 20 500 10 2. 3 4, 310, 000 2. 25 3. 48 s 0. 007 20 1, 000 4 2. 6 12, 200,000 2. 31 4. 31 s 1! Average of MD and XD. b Sample destroyed by streams.

NS=Not satisfactory for uses requiring smooth, dense nonpatterned appearance; all NS products have irregular, blotched appearance and lumpy texture.

S=Satisfaetory for uses requiring smooth, dense, nonpatterned appearance.

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